Alumni
Tomas Aronsson John Harris 
Cross section of bottom electrons in protonproton collisions in the ALICE experiment Highenergy heavyion collisions at the LHC allow for the study of the properties of the quarkgluon plasma (QGP). Heavy quarks, charm and bottom, produced in the initial hard scattering processes of the collision are excellent probes of the QGP. When heavy quarks traverse the QGP they are expected to lose energy and such energy loss is predicted to be smaller than for gluons and light quarks. On the other hand, recent experimental data indicate larger energy loss than expected. Heavy flavor... more 

Joseph Hongchul Bae Vincent Moncrief 
Senior Data Scientist NatWest Wormhole Solutions to the Bianchi IX WheelerDeWitt Equation using the Euclideansignature Semiclassical Method A Euclideansignature semiclassical method is used to construct both ground and excited state solutions to the canonically quantized Bianchi IX (Mixmaster) cosmological models. Employing a modified form of the semiclassical ansatz, we solve the relevant WheelerDeWitt equation asymptotically by integrating a set of linear transport equations along the flow of a suitably chosen solution to the corresponding Euclideansignature HamiltonJacobi equation. For the MoncriefRyan (or ‘wormhole... more 

Alexander Cerjan A. Douglas Stone 
Postdoc Penn State University Fundamental physics and device design using the steadystate ab initio laser theory In this thesis we generalize and extend the steadystate ab initio laser theory (SALT), first developed by Tureci and Stone, and apply it problems in laser design. SALT as first formulated modeled the gain medium as identical twolevel atoms, leading to the wellknown Maxwell Bloch laser equations. The result is a set of coupled nonlinear wave equations that treats the openness of the cavity exactly and the nonlinear modal interactions to infinite order. Most gain media have more than two... more 

Andrew Leister Sarah Demers 
Data Scientist Senior Freddie Mac A Search for Z' Gauge Bosons Decaying to TauAntitau Pairs in ProtonProton Collisions with the ATLAS Detector Although the Standard Model of Particle Physics has been generally successful in modeling fundamental particles and their interactions, it does not incorporate many observed physical phenomena. Many theoretical models attempting to explain physics beyond the Standard Model have been developed, several of which include one or more additional neutral gauge bosons, or Z'. The potential mass range of a Z' is quite large and for some models includes Z' masses at the TeV scale. A search... more 

Christopher McKitterick Daniel Prober 
Engagement Manager McKinsey and Company Prospects for Ultrasensitive Terahertz Photon Detection with Graphene This dissertation investigates a new scheme for the detection of terahertz (THz) photons. The vast majority of photons visible to outer space observatories occur in the farinfrared, but there do not yet exist detectors sensitive enough to accurately measure the faintest signals. I propose to use graphene, a single atomic layer of graphite, as the detecting element to observe these weak sources. As a result of its nanoscale dimensions, there are few charge carriers in graphene systems per unit... more 

Xiaoxiao Wang Tobias Golling 
Search for a supersymmetric partner of the top quark using boosted top quark identification with the ATLAS detector The Higgs discovery at the LHC has brought new attention to the hierarchy problem and the theory of Supersymmetry (SUSY). The supersymmetric partner of the top quark  the top squark (stop), is of paramount importance as it contributes the largest higherorder radiative corrections to the Higgs squaredmass. Naturalness arguments favor a light stop, making it a good candidate for discovery at the LHC. A search of the stop pair production in final states with one isolated lepton, jets, and... more 
Ana Malagon O. Keith Baker 
Search for 140 microeV Pseudoscalar and Vector Dark Matter Using Microwave Cavities Dark matter plays an important role in structure formation and composes 26.8% of the total energy density in the universe. There are many postulated particles that are theorized to be the constituents of cold dark matter; however, none have been observed experimentally. One strongly motivated particle that could be cold dark matter is the axion, a pseudoscalar with a two photon vertex. Experimental techniques to detect dark matter axions rely on a multiphoton radiative transition; in the... more 

Gennady Voronov George Fleming 
Applied Scientist Amazon The Extent of the TwoColor Fundamental Conformal Window The $SU\!\left(2\right)$ gauge theories with $N_{f}$ flavors of massless vectorlike Dirac fermions transforming in the pseudoreal fundamental representation have an enhanced global chiral symmetry and a distinct symmetry breaking pattern. These theories are expected to be qualitatively different from quantum chromodynamics (QCD) in the infrared (IR), especially with respect to the properties of the NambuGoldstone bosons (NGB). Having the potential to elucidate many features of both known and... more 

Liyao Wang Mokshay Madiman 
Heat capacity bound, energy fluctuations and convexity In classical statistical mechanics, the heuristic that in the canonical ensemble the energy distribution is sharply peaked at the mean energy is crucial in justifying the equivalence between the canonical and microcanonical ensembles. It turns out that this is closely related with the fundamental notion of a typical set and the ShannonMcMillanBreiman theorem in information theory. In this dissertation, we explore the connections between the two and establish some new rigorous results that are... more 
Colin Bruzewicz David DeMille 
Continuous Optical Production of Ultracold Vibronic Ground State Polar Molecules Polar molecules present an exciting new test bed for ultracold physics with applications in numerous fields, such as chemical reaction dynamics, manybody systems, and quantum computation. Creating large samples of these molecules that can be trapped for long times, however, remains an ongoing challenge. We demonstrate the direct formation of vibronic ground state RbCs molecules by photoassociation of ultracold atoms followed by radiative stabilization. From analysis of the relevant freeto... more 

Bernard Hicks Helen Caines 
Differential Production CrossSection of HeavyFlavor Electrons in √s = 2.76 TeV pp collisions at the LHC with the ALICE detector Recent results at RHIC seem to confirm T.D.Lee’s hypothesis that a new form of matter, the quark gluon plasma (QGP), could be formed in heavyion collisions at high energies. Heavy quarks, being formed in the early stages of heavyion collisions, form a good probe for the properties of the QGP. The energy loss of heavy quarks as they traverse the medium is predicted to be less than that of the lighter quarks. However, previous measurements of the nuclear modification factor at RHIC... more 

Lawrence Lee Tobias Golling 
Postdoctoral Fellow Harvard University A Search for Bviolating Supersymmetry in Multijet Signatures at the ATLAS Experiment With supersymmetry (SUSY) increasingly constrained, more attention is placed on alternate flavors of SUSY that allow for an unexcluded natural theory. A search for new physics phenomena in allhadronic signatures in \sqrt{s}=8 TeV pp collisions using an integrated luminosity of 20.3 fb^1 collected by the ATLAS detector at the LHC will be presented. Within the context of SUSY, gluino pairproduction gives rise to multijet final states in models that allow for violation of Rparity. Two types of... more 

Rongrong Ma John Harris 
Assistant Physicist Brookhaven National Laboratory Jet measurements in pp and PbPb collisions in ALICE LatticeQCD predicts the existence of a new form of hot, dense matter called the Quark Gluon Plasma (QGP) above a critical energy density. Such matter is believed to be created in relativistic heavyion collisions, where sufficient energy is expected to be deposited by colliding ions in a limited volume. To study the properties of the QGP, high transverse momentum (pT) partons produced at the early stage of the collisions are used as probes. Since partons are not directly measurable, jet... more 

Tianqi Shen Corey O'Hern 
Quantitative Research Laurion Capital Contact Percolation, Fragility and Frictional Packings This thesis presents four computational and theoretical studies of the structural, mechanical, and vibrational properties of purely repulsive disks, dimer, and ellipseshaped particles with and without friction. The first study investigated the formation of interparticle contact networks below jamming onset at packing fraction φJ , where the pressure of the system becomes nonzero. We generated ensembles of static packings of frictionless disks over a range of... more 
John Barry David DeMille 
Laser cooling and slowing of a diatomic molecule Laser cooling and trapping are central to modern atomic physics. It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a vast array of fields and a number of Nobel prizes. Prior to the work presented in this thesis, laser cooling had not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for a wide range of applications. The first direct laser... more 